1. Field of the Invention
The present invention relates to fluid transfer pumps. More specifically, the present invention relates to an apparatus and method for supplying fluid to a fluid transfer pump while facilitating the cleaning of the pump.
2. Description of Related Art
Fluid transfer pumps are commonly used to transfer a controlled stream of fluids from a fluid source to an outlet of the transfer pump system. A conventional fluid transfer pump has an inlet for receiving the fluid and an outlet for ejecting the fluid, typically under force. An example of a commonly-used fluid transfer pump is an airless spray painting system. A typical prior art airless spray painting system is operated under pressure. FIG. 1 is a side view of an airless spray painting system 10 according to the prior art.
In the Figure, a pump motor 12 generates the suction force used to draw in the fluid (in this case, paint) from a liquid source pick-up point, typically a container 18. The standard-sized paint supply of such prior art systems is a single one gallon paint can, typically used by non-professional painters, and a single five gallon paint bucket, typically used by professional painters.
The paint is drawn through an inlet fluid conduit such as a pick-up hose assembly 16 and into the pump intake 14. The paint is then urged into an outlet hose 20 that is joined to a spray gun 22,where the paint can be ejected from the system as a spray. The pump can use negative pressure (suction) to draw the fluid into the system and towards the outlet. Alternatively, back pressure can be used to propel the fluid forward through the outlet.
Air leakage to and from the pump assembly 24 reduces the pressure within the assembly. This reduction in pressure can cause a significant diminution in pumping force. To minimize the likelihood of air leakage and the resulting reduction in internal pressure, pressurized fluid transfer pumps are frequently constructed such that they cannot be readily disassembled.
However, a pump that cannot be disassembled is not easily cleaned. Such pump is generally cleaned by forcing a cleansing fluid, such as water or a solvent, through the pump assembly. This cleansing process can be time consuming, inefficient, and detrimental to the environment.
For example, the process usually employed to clean an airless spray painting system is for the painter to first wash the paint out of one or more paint containers. The painter then fills the paint containers with water and carries them to the location of the spray painting system. The inlet fluid conduit is inserted into the water and the spray pump motor is started. Water is pumped through the pump assembly and fluid conduits and ejected through the spray gun until the system is clean. This process must frequently be repeated to thoroughly clean the paint from the system.
The paint-and-water solution that is ejected from the system can be toxic and hazardous to the environment. The painter must either carefully collect this solution in containers for proper waste disposal, or risk fines and potential environmental damage by discarding the solution on the ground or into a drainage system.
An additional drawback to the prior art airless spray painting systems is that numerous delays occur when an exhausted paint supply is replaced with a new supply. Because commercial spray guns efficiently dispense paint, a five gallon paint bucket can typically be depleted and require replacement in approximately 8 to 10 minutes.
Perhaps an even more serious disadvantage is the damage caused to the spray pump between the time the paint is depleted from the paint bucket and the time the spray pump is shut off. Air has a lower viscosity than paint and therefore, the pump motor operates at much higher speeds when drawing air than when drawing paint. Such higher operating speeds can reduce the life expectancy of the motor.
One known solution to this problem is to provide a paint supply that is larger than the standard one gallon can or five gallon bucket. Unfortunately, such larger paint supplies are difficult to transport and to use, especially for the commercial painter. Furthermore, the significant commercial advantages to paint manufacturers and distributors of using standard-sized containers would tend to outweigh any benefits of using larger containers. An additional disadvantage of using larger paint containers is the likelihood of waste by non-professional painters, and the greater costs inherent thereto.
It would therefore be an advantage to provide a method and apparatus for rapidly and efficiently cleaning a fluid transfer pump, such as an airless spray painting system. It would be another advantage if such apparatus provided painters with a larger supply of paint while a maintaining the use of standardized one gallon cans and five gallon buckets. It would be a further advantage if the apparatus minimized the likelihood of environmental exposure to any toxic materials cleaned from the pump. It would be yet another advantage if the apparatus could be implemented as an integral part of a fluid transfer pump, or as a removable addition thereto.